A (TD-)DFT study on photo-NHC catalysis: photoenolization/Diels-Alder reaction of acid fluorides catalyzed by N-heterocyclic carbenes.

ABSTRACT: A comprehensive mechanistic study on the N-heterocyclic carbene (NHC) catalyzed photoenolization/Diels-Alder (PEDA) reaction of acid fluorides was performed in the framework of (time-dependent) density functional theory ((TD)-DFT). The 1,5-hydrogen atom transfer (1,5-HAT) during photoenolization of an ortho-toluoyl azolium salt was found to be feasible via, first, singlet excitation and photoenolization, and then, after crossing to the triplet manifold, populating a biradical dienol which allows for the formation of two ortho-quinodimethane (o-QDM) isomers due to a low rotational barrier. The (Z)-isomer is mostly unproductive through sigmatropic rearrangement back to the starting material while the (E)-isomer reacts in a subsequent concerted

SUBMITTER: Mavroskoufis A 

PROVIDER: S-EPMC10094231 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature